The present invention relates to a digital display system. The invention is especially useful in the field of timepieces with a digital display, but it may also be used in many other fields, generally whenever it may be desirable to set a digital display to any selected value. The invention relates in a preferred embodiment to the setting of a timepiece having a presettable digital display.
The principal qualities sought in this kind of correction are simplicity and speed. Thus, the user is not happy if he has to select individually each of the digits of different significance which the number may comprise and then to cause the successive values of the selected digit to run off in sequence until the value which it is to take in the desired corrected number is reached. It is not seldom that he is obliged to make several attempts before arriving at the required result. He is still less happy when, as in those arrangements which are generally used at present, he must make all the values of the number run off unit by unit.
The object of the invention is to overcome these disadvantages by simplifying the necessary manipulations, in particular at the level of the selection of the digits in which intervention takes place. Moreover, the invention has the object of reducing the number of values which it is necessary to cause to run off in succession for each digit in order to effect a given change in the number and, therefore, of reducing the total duration of the changing operations.
This latter advantage makes itself felt above all in connection with the limitation of the speed of counting which the electronic circuits controlling the display may impose and with the minimum interval of time between two successive values which has to be allowed for the digits to appear legible in their new value. For example, if the values of the digits are visually displayed according to the state, coloured or not, of electrochromic segments forming the digits, the passage from one value to another demands in practice, for the electrochromic cells used at present, a time of the order of one second, taking account of the time necessary for the segments to be able to change state, that is to say for segments which are previously effaced or blanked out to be able to appear coloured and, conversely for segments in the coloured state to be able to be completely blanked out.
On the running-off of the displayed values in succession, the invention enables this relatively slow speed, which is essential for the quality of the display and easy reading of the digits, to be observed, while reducing the time necessary for correction.